Organic polymers with a conjugated backbone form an important class of electronically conducting materials. Conduction mechanism in these types of polymers involve .pi.-electrons which overlap along the conjugated chain to form a .pi.-conduction band. These materials are intrinsically semiconductors, and can be made highly conducting only after chemical doping. To date semiconducting polyacetylene remains the most extensively studied of the conjugated polymers due to the availability of its flexible films, the high conductivity upon doping, and the reversibility in the electrochemical oxidation (p-type doping)--reduction (n-type doping) process. The chemical doping of polyacetylene film with electron acceptors such as AsF.sub.5 and iodine, or electron donors such as sodium, gives values of conductivity up to 10.sup.3 .OMEGA..sup.-1 cm.sup.-1 at room temperature. Unfortunately, there are some practically inconvenient features associated with polyacetylene. Probably the most disadvantageous feature of all is its inherent inconvenient instability towards atmospheric oxidation. This instability hindered the scientific study and its possible technological exploitation. Therefore, a great interest has been generated in the exploration of related polymers with a great oxidative stability as well as thermal stability and processability while retaining the interesting electrical properties.
Based on these considerations, the most pronounced polymers belong to the category of aromatic polyarene polymers. Some examples are: poly(paraphenylene), Shacklette, L. W., Chance, R. R., Ivory, D. M.; Miller, G. G.; Baughman, R. H., Synth. Met., 1980, 1, 307; polypyrrole, Diaz, A, Kanazawa, K. K.; Gardini, G. P., J. Chem. Soc., Chem. Commun., 1979, 635; poly(2,5-thienylene), Yamamoto, T., Sanechika, K., Yamamoto, A., J. Polym. Sci., Polym. Lett. Ed., 1980, 18, 9; Lin, J., Dudek, L., J. Polym. Sci., Polym. Chem. Ed., 1980, 18, 2689; poly(phenylquinoline), Wrasidlo, W., Norris, S. O., Wolfe, J. F., Katto, T., Stille, J. K., Macromolecules, 1976, 9, 512, polyselenophene, Yoshino, K., Kaneto, K., Inoue, S., Tsukagoshi, K., Jap. J. Appl. Phys., 1983, 22, L701, and polynaphthalene, Aldissi, M., Liepins, R., J. Chem. Soc., Chem. Commun., 1984, 255. Among these polyaromatics, poly(phenylquinoline), and its derivatives are generally the most thermal oxidative stable polymers. Films based on these poly(phenylquinoline) derivatives have been reported to exhibit conductivities of up to the order of 50.OMEGA..sup.-1 cm.sup.-1 upon doping with sodium, Tunney, S. E.; Suenaga, J.; Stille, J. K., Macromolecules, 1983, 16, 1398, Denisevich, P.; Papir, Y. S.; Kurkov, V. P.; Current, S. P.; Schroeder, A. H.; Suzuki, S., Polym. Prepr., Am. Chem. Soc., Div. Polym. Chem., 1983, 24, 330-1, a seventeen orders of magnitude increase in conductivity compared to the undoped material. Surprisingly, to date the nonsubstituted polyquinoline of the present invention has not yet been made in spite of many substituted polyquinoline derivatives having been successfully synthesized, Stille, J. K., Macromolecules, 1981, 14, 870-80.
It is known that polyquinoline derivatives can be prepared by a Friedlander synthesis, Friedlander, P. Chem. Ber. 1882, 15, 2572, which is a base catalyzed reaction between 2-aminobenzaldehyde and acetaladehyde. This type of reaction was found to undergo a far better satisfactory result with an acid catalyst of poly(phosphoric acid) than base catalysis in the polymer synthesis with a higher molecular weight product and a higher yield. Thus, homopolymer or copolymer of quinoline derivatives can be readily prepared by a condensative cyclization reaction between aromatic o-amino ketone and ketomethylene compounds to construct quinoline moieties. However, this method is most suitable for the synthesis of substituted polyquinolines but not for the nonsubstituted polyquinoline due to the side reaction of the aldehyde functionality if an o-amino aldehyde is used instead of o-amino ketone.